Obscured by Clouds. The rough and ready blog of a cloud benighted biologist and amateur astronomer. Astroblog will cover my interests in astronomy, biology and Life, the Universe and Everything.

Wednesday, August 31, 2011

Comet Elenin in STEREO H1B (August 25 and 26)

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 25. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines and weird loopy bits are imaging artifacts.

Elenin passes through the image field of view of the STEREO H1 Behind imager on August 26. Click to embiggen. Image processed from NASA/STEREO raw images using ImageJ. Inverted image, dark lines and weird loopy bits are imaging artifacts.

I've plotted the intensity of comet Elenin images relative to a reference star (indicated on the image from the 26th) from the 18th to the 26th. I have the data from the 27th, but the comet passes over a bright star and I can't separate out the brightness of the comet from the star.

There is some dropped points on the 23rd when the imaging arefact of Mercury passed over the comet and reference star images. Again, click to embiggen.

As I've stated before, on calibrated images the comet has faded over 80% since the 19th, however, using this method of normalising (compared to how I did it on the calibrated images earlier) the drop is more like 70%.

Again, we have to factor in that it is further away from the H1B camera despite being closer to the Sun. I have not explicitly tried to calculate magnitudes, especially since Elenin is an extended source.

Anyway, important things to notice: The Coronal Mass Ejection that did all the fancy tail twirling hit between two flare-ups of the comet. The second peak (coming after the arrow showing where the peak CME hit, comes after the CME has washed over it (ie the big peak is not an artefact of the CME brightness adding to the comet, it genuinely gets brighter). The next peak is an aretfact form the comet crossing in from of a star, but the peak after that, although it crosses a star early, is probably also a flare.

Images from STEREO on the 27th (image right) don't show the same nucleus elongation that you see in Michaels images on the 27th, but with the STEREO images it's like looking through a pair of 7x30 binoculars compared to the telescopic images. I don't expect to see much until later images.

Hi Ian, you're probably already aware but I've only just discovered that some of the 2012 people have latched onto Comet Elenin.

The website at elenin.org really does contain some incredible rubbish. At one point they claim "[Elenin] is on a 3,600 year orbit around the galaxy". I make that around 50 times the speed of light! They also think we are from the Sagittarius Dwarf Galaxy and that the Milky Way is "slanting sideways" due to a merger between the two. Arggh.